The inventive concept relates to an oscillator, and more particularly, an oscillator including a varactor circuit and method of operation thereof.
An oscillator including a phase locked loop (PLL), for example, is a circuit generating oscillation signals (or clock signals) used to send data from a transmitter and restore data in a receiver. In this case, the PLL included in the oscillator may be sorted as a ring PLL, an LC-PLL, etc.
When the LC-PLL includes a varactor circuit, a resonance frequency of the LC-PLL is determined by a capacitance of the varactor circuit and an inductance of an inductor. The capacitance of the varactor circuit changes depending on control voltages, and a C-V property of the varactor circuit may be changed depending on a Process-Voltage-Temperature (PVT) change. Thus, irregularities in changes of frequencies of the oscillation signals according to the control voltages may occur.